Speaking of declining campaigns: the Washington Post reports on the long, slow erosion of confidence in Jeb Bush’s 2016 presidential prospects among the GOP donor class.

Bush’s super PAC, Right to Rise, still may have the deepest pockets in the race thus far. But according to the Post, Jeb’s fifth-place showing in a recent national poll is prompting warnings from establishment Republican donors that his continued middling performance is on the verge of sparking some serious divestment:

The warnings from top donors come as Wisconsin Gov. Scott Walker’s exit from the race re­focused the battle within the GOP’s establishment wing as one between Bush and his former protege, Sen. Marco Rubio (R-Fla.). Right now, the momentum appears to be behind Rubio, who has jumped ahead of Bush in most polls. At least a third of the bundlers who signed up to raise money for Walker have switched their allegiance to Rubio, while a smaller number have gone with Bush, according to people familiar with the discussions.

A large part of this skittish dynamic among party establishment donors — it’s not even October, remember — is surely fueled by the Donald Trump panic of the last couple of months. Rubio’s recent bump wouldn’t be terribly extraordinary in itself, but when one considers the potency of the popular discontent that’s propelled Trump and Ben Carson to the top of the polls, the fact that an actual politician is now attracting double-digit support suddenly seems like big news. Which in itself is a pretty remarkable development.